Flip-chip mounting has been known as a method for mounting a device chip including a functional element such as, for example, an acoustic wave element on a mounting substrate as disclosed in, for example, Japanese Patent Application Publication Nos. 2004-96456, 2004-207674, 2006-203149, and 2010-245739.
To reduce the chip area of the device chip, the size of the pad on which a bump is bonded is demanded to be reduced. However, the reduction of the pad size decreases the bond strength between the bump and the pad.